This invention relates to a system for controlling the air flow within a building and in particular to a system which detects smoke, fire, or high heat and automatically reduces the air flow within a building.
In the case of detecting smoke, fire, or high heat within a building it is desirble to cut off the flow of air within the entire building to prevent smoke from circulating, fire from burning, and to retard heat flow. Automatically closing fire dampers for air ducts are well known, examples of which are disclosed in the following U.S. patents: Dean, Jr. et al., U.S. Pat. No. 3,687,055; McNabney et al., U.S. Pat. No. 3,785,272; Maxson, U.S. Pat. No. 4,397,223; and Barchechat et al., U.S. Pat. No. 4,545,363. However, these automatic closable damper devices only operate in the room in which the fire occurs. Also, some of these prior art devices are only activated upon the melting of a fusible link which may not melt in time to prevent smoke from escaping through the air ducts to other parts of the building. Additionally, most buildings have a ventilation system, such as an air conditioner or a furnace, which includes a blower for circulating air in the building. If the blower is allowed to operate during, for example, a fire the circulated air will feed the fire. Therefore, in addition to closing the vents it is also advantageous to disable the blower.